A reconfigurable optical add/drop multiplexer is one of core devices in a wavelength division multiplexing optical interconnection system, and a hitless (Hitless) wavelength selective switch is a critical element of the device. A hitless wavelength selective switch in conventional optical communications is mostly based on a switch technology such as a micro-electro-mechanical system (MEMS), has a large volume and a low speed, and is unsuitable to be used for inter-chip and on-chip optical interconnection wavelength division multiplexing networks. An inter-chip, or particularly, on-chip optical interconnection needs a hitless wavelength selective switch that has a small volume and a quick speed, and that is convenient for high-density integration. In addition, a wavelength selective switch based on an InGaAs/InAlAs five-layer asymmetric coupled quantum well second-order or fourth-order series microring structure is incompatible with a silicon-CMOS craft, and a wavelength adjustable range is not large. Therefore, the wavelength selective switch is also unsuitable for a high-density integrated optical interconnection.